Manufacture of concrete



Patented Jan. 22, 1929. l

" UNITED STATES PATENTOFFICE.

MARCEL LEVY, or GENEVA, SWITZERLAND, nssrenon T PRODOR FABRIQUE DE rnonnors ORGANIQUES s. A., or GENEVA, onn'ron orennnvn, SWITZERLAND,

A CORPORATION OF SWITZERLAND.

MANUFACTURE OF CONCRETE.

16m m'awingt Application filed November 2, 1922, Serial No. 598,651, and in Switzerland November Reinforced and non-reinforced concretes hitherto used iorthe construction of pipe' lines,- containers for liquids and hydraulic prises the incorporation under the action of heat of a selected or specially prepared hard pitch with graded filling materials, namely, material of large size, for example coarse broken stone, fine material, for example powdered stone, and intern ediatematerial, for

example sandor gravel.

The improved concrete forming the, subject of the present invention possesses considerable and numerous advantages in comparison with the concretes hitherto known, for example it is possible forthe first time to produce reinforced and nonreinforced concretes, which in themselves and without the use of any coating can resist the action of chemical substances and in particular acids and even concentrated acids.

Further these concretes canbe produced with rather smooth surfaces which are impermeable to water even at a pressure above 15 atmospheres, Without the use of any coating.

Concretes produced in this manner are at least as strong as the usual cement concrete.

Three samples each were tested ata temperature of 20 and 60 C. and gave the fol.- lowing results Bending stress ex- Crushing pressed in stress kg] kg. per sq. cm

It may be here remarked thatthe manufac-- concrete may be subjected in use.

aggregates is well known and the use-of pitch as a binder is well known.

Further, pitches of various degrees of hardness are available or have been proposed.

In almost every case, however, for present commercial requirements the pitch to be employed,.although it may be hard pitch, is yet as regards the present invention compara-- tively soft.

I have found it necessary when pitch is to beincorporated as a binding material for the purpose of obtaining the. benefit of the present invention to employ a pitch which is harder than the ordinary pitches, such for in stance as a pitch which is heated to about 350 C. for driving oil the constituents volatile at that temperature. Such a pitch when tested at the maximum temperature of use, say with the Brinell machine with a ball of 20 nnn. and a loado't' 100 kgs, should not give a reading below as the Brinell hardness figure and preferably not less than and itssoftening point as indicated by a rapid decrease in the Brinell hardness figure should not occur below about C. or some higher temperature according to the use to which the composition is to be put; otherwise a composition having mechanical properties at the temperature of use similar to cement concretecannot be obtained. i

A method of producing such a concrete will now be given by way of example.

In order to produce a cubic meter of concrete, We heat to the melting point for example from 250 to 350 kgs. colophony, sulphur, gum resin or. similar products, gas pitch, it being essential that the product used remains very hard at the temperatures to which the To the liquid mass are added at about 200 C. 1700 kgs-of broken stone and about 700 kgs. limestone powder and heat applied whilst stirring constantly. The homogeneous mass obtained is cast as for ordinary cement concrete in the hot condition into moulds or shells and sets on cooling and forms a structure of great strength, which may even exceed that of or dinary cement concrete; The improved concrete may also be produced in another'way. F or example, coarse. grained filling material such as broken stone are first heatedto about 200 C. and added to the mixture of the organic binding agent and concrete is to be subsequently exposed; a resalt of this is that the softening temperature of the binding agent forms an important factor; as upon this depends the temperature to which the concrete may be heated without: losing its strengtln For this reason the pitch binding agent,according to thecircumstances,

may be subjected o a special treatment in order to increase its softening temperature.

It is known, for example, that the softening temperature of the various kinds of pitch can be increased by treatment with lime and that of tar distillation products by conducting a current of hot air through the mass at the end of the distillation, the air removing the readily volatile constituents. i

It is also known that by treating pitch with hydrochloric or sulphuric acid, the softening temperature of this substance is increased. Pitchmay also be subjected to a preliminary treatment in order to purify it and particularly to remove therefromthe soluble substances which it may contain. For this purpose it may be washed with cold or hot Water or with cold or hot solutions of mineral acids or soda. In order to render the pitch entirely acidresistant, it may also be previously treated with concentrated mineral acids and then washed with flowing water, but whateverpreliminary treatment be given in the way of washing with water or acids, if the pitch is not hard enough according to the tests given above it must be made sufi'ioiently' hard, for example, by heat. Instead of broken limestone all kinds of broken stone, broken bricks or tiles, lava,

stoneware, granite, quartz, cork, coke, coal, slag, gravel, in fact any solid rubble material and so forth may be used. Brokenminerals with sharp edges and rough surfaces, give stronger concrete than gravel with smooth surfaces. I The limestone powder may also be re laced by other still more finely powdered su stances such as clay, stoneware, pumice stone, graphite, coal, soot, kieselguhr,very

fine sand and powder.

The choice of coarse and fine granular constituents for the new concrete is of great importance.

For instance with hard non-porous limeso forth or any other inert stone in broken up and pulvrulent condition 250 kgs. hard gas pitch are required for one cubic meter of eoncrete,'whereas withporous, soft limestone which can ,be. sawn about 400 kgs. are required and with brokenpumice stone and pulverized kieselguhr about 500 --kgs; of'hard gas pitch are necessary. From this it will be seen that the relative proportions of the constituents also depend upon the composition of the mixtures. Care must however be taken that with the coarse gran ular material sufiicient finely powdered substances are mixed in order to obtain a thick pasty mass in which the coarse stones remain in suspension and are uniformly distributed.

In order to prevent contraction of the concrete when setting as much coarse granular and pulverized filling mater al as possible is used.-

The improved concrete according-to the present inventionmustnot be confused with.

the mixtures containing tar which are used for coating roads, pavement-s or roofs or also for engine foundations. Theseinixtures necessarily must be more or less soft, plastic and resilient and cannot be used in building constructions in place or ordinary cement concrete for the construction of large containers, water pipes, high pressure pipes (up to 20 atmospheres) dams, dykes, subaqueous structures and so forth.

Asphalt pipes are already in existence which are constructed of cement, iron, glass or wood and then'coated either externally or internally with artificial or natural asphalt or asphalt or tar pulp, which are rolled together a number of times, to form a pi e which actually is composed of layers of pu p and asphalt or tar.

These'facts assist in bringing out the feature of the present invention still more as here the natural or artificial asphalts, by reason of their presence, do not offer much resistance but are pliable and plastic, so that in an unhardened condition they cannot be used in the manufacture of pipes asthey are not suificiently strong; for this reason itis necessary-to reinforce them with wood, cement concrete,'glass or pulp. The only kinds of pitch which at present are able to be sold are pitches which are'not extremely hard. For

this reason .pitch which is-prodnced as a hard pitch before it is placed on the market is softened by the addition of oils. The pitch which is required-for the present invention as opposed to this softened pitch m'ustbe extremely hard.

According to the new process it is possible to obtain pipes, without the. necessity of strengthening them, which are stronger than cement pipes and this even at the highest temperatures producedv by the heat of the sun.

Hereinafter there is given an example of a pipe which has been produced by means of gas tarthe distillation of which has been carried through to a sufiicient extent in order to obtain a pitch which is very hard and remainshard at temperatures of 80 C. and

over. I

With'this very hard pitcl'n which is very brittle and shin there is obtained when it is melted andmixed with broken stone, sand 3500 kgs. is necessary and this at temperatures of and 60 C. the pipe being loaded on its upper part along a length of 50 cm. F or an aged'ordinary cement pipe which was cast in the same mould as that which was used for the new concrete i. e. which had exactlythe same dimensions and subjected to loading under the same conditions only 2500 kgs. were necessary to produce the fracture.

From this will at once be seen the importance-of the new concrete for the construction of pipe lines of all descriptions as the pipes can be produced at almostthe same price as ordinary cement pipes, whilst the pipes of the new concrete are stronger, more resistant against chemical action and at the same time are impermeable towater and possess very smooth surfaces.

There are a number of patents in existence for converting tar containing 7 bituminous substances into artificial asphalt. In all these patents endeavours are made to' give these products the properties of asphalts. These must be soft and plastic and therefore vary theirhardncss in summer and winter in an appreciable manner. To the natural as'- phaltic earths there is always added a certain quantity of very soft bitumen when the cast, asphalt, is being 'preparedso that it doesnot crack inthe cold.

Owing to the fact that natural or artificial asphalts are soft and .plastic they cannot without hardening be used for the preparation of concrete, for. the construction of pipe lines, containers of all kinds and similar. structures.

In order to illustrate the above better, experiments were made for the production of concrete for the construction of pipe lines and so forth with different asphalts especially Seyssel asphalt, as usedfor the production of cast asphalt slabs. These concretes were prepared as follows:

The asphalt was melted, then mixed with broken stone in order to obtain a thoroughly uniform mixture in which the stones could no longer sink. This'concrete is thus similar to that used for the production of road paving. A number of square plates 36 X 12 cm. were produced which were tested as regards bending and pressure. The following are the results obtained by these tests:

Furthera pipe wasconstructed from the" same asphalt'concrete and having a diameter of 30 cm. a length of 1 m. and a thickness of 4 cm.; at a temperature of 25 C. this collapsed, under a small load.

Asphalts can be used for the, production of the new concrete according to the present invention but they must be previously treated in order that they may be hardened, so that at a temperature to which'the concrete may be exposed later they are hard: i. e. the

' asphalts will no longer possess properties pe culiar to asphalts and can no longer be used forcoating roads and so forth.

Hard pitch which is suitable for the present invention, cannot replace asphalt as it is too friable, will crack too easily and cannot be used for coating roads.

The presence of coarse gravel, or better of broken stone plays a very important part in the preparation of the new concrete. 7

As a general rule it is possible to say that: (1) the more compact the structure of the solid body the smaller will be the quantity of pitch required; (2) the greater the propor tion of the solid body in the filling material, thesmaller will be the liability of the concrete to crack.

In order to facilitate the combination of an old pitch concrete with a new one the surface of the old concrete may be coated with is still hot and viscous. This can be done in the following manner:

The new still viscous and soft layer of concrete is separated from the old layer by a trowel and asphalt is poured into the small intervening space. In this manner an effective comblnation is obtained between the two layers whilst the connecting layer is at the same time also elastic.

The following are a few examples for preparing compositions for particular uses according to the present invention.

Example for the production of an acid resisting concrete, which will resist the action of concentrated hydrochloric acid.

stirring, with 1200 kgs. broken stoneware or' pieces of burnt clay or quartz, of which the separate pieces have a thickness of from 1 to 30 mm. as obtained from the stoneccrusher. In order to prevent ,these large pieces from sinking in the mass very fine powdered stonewareis added during the continued heating so that the mass becomes thick and pastyand the coarse granular solid constituents remain in'suspension. As soon as the mass becomes so thick that the solid constituents no longer separate from the liquidparts it is poured whilst stillhot into metal lined Wooden shells stone powder andthe like.

- The new concrete resists frost and refriger- I The new concretelnay also struct containers of any desired capacity,

pipe lines and the like which will resist the action of acids and especially concentrated hydrochloric acid "so that even after'being, in use for many months they do not show the least signs of decay. I l H Instead of broken stoneware, lava, pumice stone, quartz and'so forth may be used which will resist acids. also may be replaced by kieselguhr, pumice ation as also changes of temperature.

beam constructed of the above concrete 2 m. for

in length and some days in a 10 cm. wide was exposed freezing-chamber at a temper- C. after which it was placed in hot water above 40 0., the beam resisted this change of temperaturerwithout any injury. A furthertest wasmade with a piece of concrete which was completely covered with ice. This piece was then exposed to the action of steam for melting the ice and was not damaged by this treatment.

lining for containers of cement concrete. For

this purpose a layer of pitch concrete is poured on the cement to a thickness of a few centimeters, so as to cover the whole inner The new concrete a container constructed in this manner was I being observed.

three feet in diameter. In the joints may be em-' by leavearthenware and which is "case of wooden shells or The powdered stoneware be used as a in usefor many months without any cracks This tank was about three feet deep *and case of large containers: ploy'cd between sections of the'linin ing gaps and filling them with a plastic material, for example asphalt. I

In order to obtain quite smooth surfaces which are even smoother'than those of glazed of great importance in the case of pipes, the new concrete is poured into previously heated moulds or shells provided with smooth surfaces. Inthe moulds polished wood may be employed or better still wood covered with sheet iron or the like.

'The new concrete has nothing incommon with tar products which are used'for coating or paving roads, pavements or roofs or for engine foundations; usually be comparatively soft and elastic and These products must 4 cannot be used 1n place of ordinary cement concretein building construction and for the construction of dams, dykes, large containers,

and high pressure Water pipes up to 20 atmosheres.

What I claim is: I As a new article concrete having mechanical strength substantially equal to that'of cement concrete, com prising a brittle pitch dried 'so'as to remain hard at temperatures of 80 C. said concrete also containing an aggregate and a substantial portion of fine powder sufficient to form a thick pasty mass with the pitch ingredient.

In testimony whereof I have afiixed my signature.

DR. MAROEL LEVY.

of manufacture, a pitch a 

